| 15939088 |
DeFazio RA, Hablitz JJ: Horizontal spread of activity in neocortical inhibitory networks. Brain Res Dev Brain Res. 2005 Jun 9;157(1):83-92. Epub 2005 Apr 19.
In the presence of 4-aminopyridine (4-AP) and excitatory amino acid receptor blockers, GABAergic networks in the neocortex give rise to large spontaneous GABA-mediated depolarizations. We used voltage-sensitive dye techniques to explore the network properties of depolarizing GABA responses. Voltage-sensitive dye signals demonstrated that the superficial layers support the propagation of depolarizing GABA responses, with only minimal signals detected in deeper cortical layers. GABA responses propagated at a speed of 2.7 +/- 0.2 mm/s, a rate intermediate to fast synaptic transmission and spreading depression. Changes in the extracellular potassium concentration altered the propagation speed of the depolarizing GABA response. Taken together, these data support a role for both direct synaptic action of GABA at GABA (A) receptors and nonsynaptic mechanisms in the generation and propagation of depolarizing GABA responses. |
1(0,0,0,1) |